Variable lenses, e.g., multiple focus lenses and zoom lenses have traditionally employed one or more non-deformable (i.e., rigid such as glass or polycarbonate) lens elements which are moved along an imaging axis by forces often supplied by a motor.
In recent years, motorless electro-responsive lens elements have attracted increased attention of researchers and designers of optical systems. One type of motorless electro-responsive lens element is the “fluid lens” lens element which in one form can include a rigid or elastomeric membrane filled with one or more fluids having indices of refraction greater than 1. Fluid lens element technology has attracted the attention of many designers of optical systems who generally see traditional solid lens elements and motor equipped systems as bulky and energy hungry. With the proposals for fluid lens elements there have been proposed various methods for varying an optical property of a fluid lens element for integration into an optical system.
According to a process of electro wetting, a fluid lens element is provided having at least two immiscible fluids and a voltage is applied to the fluid lens element. A surface tension of the fluid lens element changes as a result of the voltage being applied, bringing about a change in the curvature of an interface between the at least two fluids.
In U.S. Publication No. 2008/0144185, a fluid lens element is described having a deformable membrane partially defining a cavity that holds optical fluid. An actuator assembly comprising an actuator is provided for imparting a force on the deformable membrane.